A Dog’s Nose
for Sniffing Out Signs of Diabetes….Can it
replace the OGTT?
Technology based on a dog's ability to smell can
detect a range of illnesses, including diabetes,
cancer and schizophrenia
SMELL is an important indicator of well- being,
and has been used as a diagnostic tool since ancient
times. The Romans gave the distinctive odor of
renal failure its own term — “fetor
hepaticus” — while even today many
diseases are known to have a characteristic smell,
such as a “sweet acetone breath” for
diabetes, and “putrid breath” for
streptococcal throat infections.
But now this principle is being harnessed with
the latest technology to provide a sophisticated
way of diagnosing disease. In one advance, researchers
at the University of Rome have designed an electronic
nose (“e-nose”) for detecting lung
cancer in patients. In recent trials at the Forlanini
Hospital, the e-nose correctly identified patients
with lung cancer tumors simply by smelling their
breath.
The “nose” is actually a chemical
sensing system — a spectrometer —
and a computer system that matches patterns of
smells. The technology is pretty much the same
whether you are detecting lung cancer or sniffing
for salmonella. Each system is “trained”
to pick up certain chemical signatures, usually
a complex combination of smells. People with lung
cancer tend to exhale a mixture of alkanes and
benzene derivatives — the University of
Rome e-nose has been calibrated to pick up these
chemical signatures.
The e-nose is non-invasive, quick and apparently
accurate (the lung cancer patients were diagnosed
in a minute). The technology is based on the olfactory
model of dogs, known for their acute sense of
smell (the human nose is too blunt an instrument).
In a case reported in The Lancet some years ago,
a dog was said to have “discovered”
a melanoma on her owner’s leg. The border
collie/doberman cross kept on sniffing and even
biting the mole, so finally her owner went to
the doctor to have it looked at — a biopsy
confirmed that the mole was in fact a malignant
melanoma. “This dog may have saved her owner’s
life by prompting her to seek treatment when the
lesion was still at a thin and curable stage,”
wrote the researchers.
While it may not be practical to have a canine
cancer-sniffer in every dermatology clinic, the
fact that melanomas and diabetes can be detected
through smell means that one day an e-nose could
be adapted to do the same job.
Professor Donald Broom, of the department of clinical
veterinary medicine at the University of Cambridge,
is currently looking to test the viability of
using dogs to sniff out prostate cancer in urine
samples. Again, if dogs can detect prostate cancer,
then so could an electronic nose. The advantage
that e-noses have over dogs is that they don’t
get tired (sniffer dogs can suffer from smell
“burnout’’ if they are kept
working on a smell for too long). Electronic noses
could be used as a diagnostic tool for other pathologies,
too, such as diabetes, liver cirrhosis and renal
failure — each has its own chemical signature.
The team at the University of Rome is also studying
the correlation between schizophrenia and skin
odor. It was nearly 30 years ago that scientists
first discovered that schizophrenic patients have
a specific skin odor. Now that the technology
is available, this information can be put to use.
According to Professor Corrado Di Natale, who
is leading the study: “We have been measuring
axilla “armpits” odor in patients
and results are encouraging.”
He envisages the e-nose being developed to screen
smokers and other high-risk groups for lung cancer
as part of a routine check-up. Of course, it may
not replace the precision offered by scans and
blood tests, but it could be a useful tool for
early detection.
But even at this stage — with a correct
diagnosis in one minute — the e-nose future
looks promising. For information on e-noses: www.nose-network.org
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